ANATOMY

• What percentage of the brain's blood supply is provided by the internal carotid artery?


  70%
• What is the pathway for the anterior circulation blood supply?

  Aorta > brachiocephalic > common carotid > internal carotid
• What artery supplies 30% of the brain's circulation?

  Vertebral arteries
• What structures are associated with the blood supply to the brain?

  Foramen magnum, carotid canal, foramen transversarium
• What are the main vessels in the anterior circulation?

  • Posterior communicating artery
  • Internal carotid artery
  • Middle cerebral artery
  • Anterior cerebral artery
  • Anterior communicating artery
• What is the clinical effect of an infarct in the anterior cerebral artery territory?

  Contralateral lower limb weakness and sensory loss
• What area does the middle cerebral artery supply?

  The majority of the lateral cerebrum
• What are the clinical effects of an infarct in the middle cerebral artery territory?

  Contralateral head, neck, trunk, and arm weakness
• What is expressive aphasia associated with?

  Damage to Broca’s area
• What is receptive aphasia associated with?

  Damage to Wernicke’s area
• What regions are affected by the deep branches of the middle cerebral artery?

  Internal capsule and basal ganglia
• What is the clinical effect of a small stroke in the deep branches area?

  May cause dramatic effects like hemiparesis
• What are the vessels in the posterior circulation?

  • Pontine arteries
  • Posterior cerebral artery
  • Superior cerebellar artery
  • Basilar artery
  • Posterior inferior cerebellar artery
  • Anterior inferior cerebellar artery
  • Anterior spinal artery
• What is the territory of the posterior cerebral artery?

  Inferomedial temporal and occipital lobes
• What is the clinical effect of an infarct in the posterior cerebral artery territory?

  Homonymous hemianopia
• What are carotid and vertebral angiograms used for?

  To look for and treat pathology
• Name one pathology that carotid and vertebral angiograms can detect.

  Aneurysms
• What is another pathology that can be identified using angiograms?

  Vascular malformation e.g. fistula
• What is a third pathology that angiograms can help diagnose?

  Acute ischaemic stroke
• How is a catheter used in angiography?

  It is inserted into the femoral artery
• Where does the catheter go after being inserted into the femoral artery?

  It reaches the internal carotid or vertebral artery
• What happens after the contrast is injected during an angiogram?

  Images are taken
• What must you know to interpret an angiogram?

  The vessel and projection of the image
• Which vessel is viewed for the anterior circulation?

  Internal carotid artery (ICA)
• Which vessel is viewed for the posterior circulation?

  Vertebral artery
• What are the two projections used in angiograms?

  Frontal and lateral
• Why does the brain require around 14% of cardiac output?

  To meet its high metabolic demands
• What is the cerebral blood flow (CBF) maintained at?

  50 mL/100g of brain tissue/minute
• What causes changes in the muscular wall of vessels?

  The pressure within the vessels
• What is the autoregulatory cerebral perfusion pressure (CPP) limit?

  Around 60-160 mmHg
• What happens when pressure increases in the vessels?

  Vasoconstriction occurs, reducing CBF
• What occurs when pressure decreases in the vessels?

  Vasodilation occurs, increasing CBF
• How does CBF behave outside the CPP autoregulatory limits?

  It becomes dependent on mean arterial pressure
• What does autoregulation allow for the brain?

  Maintenance of blood flow to the entire brain
• What factors have localized effects on specific brain regions?

  Carbon dioxide and hydrogen ion concentration
• What effect do carbon dioxide and hydrogen ions have on blood flow?

  They cause vasodilation
• What is the process of myogenic autoregulation?

  • Pressure increases: vasoconstriction occurs, reducing CBF
  • Pressure decreases: vasodilation occurs, increasing CBF
• What are the key components of cerebral blood flow regulation?

  • CBF maintained at 50 mL/100g/min
  • Autoregulation between 60-160 mmHg CPP
  • Local factors like CO2 and H+ affect specific regions
• What are the superior boundaries of the anterior triangle of the neck?

  Inferior border of the mandible
• What is the posterior boundary of the anterior triangle of the neck?

  Anterior border of sternocleidomastoid